Protesters hold up portraits of Nigerian villagers as they listened to speakers in front of a Chevron gas station in San Francisco Monday on October 27, 2008.

Photo: Brant Ward, The Chronicle

Protesters hold up portraits of Nigerian villagers as they listened...

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Carling Sothoron of San Francisco held a picture of a Nigerian boy during the gathering. Over 100 protesters gathered on the corner of 9th and Howard Streets in San Francisco Monday October 27, 2008 to protest against Chevron Corp. It is the opening day of a trial here by Nigerian villagers against actions by Chevron including a shooting in 1998.

Photo: Brant Ward, The Chronicle

Carling Sothoron of San Francisco held a picture of a Nigerian boy...

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Supporters of a lawsuit against Chevron protested in front of a gas station in San Francisco.

Photo: Brant Ward, The Chronicle

Supporters of a lawsuit against Chevron protested in front of a gas...

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A speaker talks to protesters gathered in front of a Chevron gas station in San Francisco.

Chevron Corp. unleashed a "notoriously brutal and vicious" Nigerian military force on peaceful protesters at an offshore oil rig in 1998, a lawyer for a group of villagers accusing the company of human-rights violations told jurors in San Francisco on Tuesday.

Two men were killed and two were wounded by shots fired by troops summoned by Chevron's Nigerian subsidiary on the fourth day of a confrontation with more than 100 villagers. Jurors assessing the plaintiffs' claims of assault, torture and wrongful death must decide whether to believe their description of a nonviolent demonstration or Chevron's account of a violent hostage-taking.

In his opening statement in U.S. District Court, plaintiffs' lawyer Dan Stormer called the incident an unprovoked attack on unarmed men who had gone to the offshore platform to negotiate because "they were watching their communities die" from poverty and pollution. The troops, Stormer said, were "people paid, housed, fed and supervised by Chevron."

The company's lawyer Robert Mittelstaedt, countered that Chevron was forced to respond to "a hostile, illegal invasion that put the workers' lives at risk."

"What this case is about is the right and duty of a company to protect its workers," Mittelstaedt said.

The 19 plaintiffs - the two wounded men, the family of one of the slain men, and relatives of a fourth villager who was allegedly beaten and tortured in custody - are suing the San Ramon company under the Alien Tort Claims Act of 1789, which allows foreigners to seek damages in U.S. courts for international human rights violations.

The shootings took place in May 1998 on a barge tethered to Chevron's Parabe platform, 9 miles off the coast of the African country's oil-rich Niger Delta region. The men from nearby villages had gone to the platform four days earlier because, Stormer said, "they needed jobs and they needed protection (for) the environment."

Because of Chevron's drilling and dredging practices, the attorney said, salt water was polluting village wells and killing fish, the soil was turning acid, and trees were dying. He said Chevron Nigeria had refused to meet with delegates from the villages, so they "decided to have a peaceful protest" and carried only placards onto the barge.

After three days, he said, a company official sent a fax to the U.S. Embassy saying the villagers were unarmed and the situation was calm.

But Mittelstaedt said about 150 villagers took over the platform, the barge and a tugboat, cutting off communications and access to a helicopter pad to prevent employees from leaving.

One man "poured diesel fuel over the barge and threatened to set it on fire," and a Chevron employee "saw invaders with knives," the lawyer said, displaying a photo of a man apparently carrying a sheathed knife.

Mittelstaedt said the group had written two threatening letters to Chevron Nigeria several weeks earlier. One mentioned the possibility of a "mass riot" if the company refused to negotiate, and the other asked, "Which language do you now understand - is it violence or sea piracy, war or peace?"

Tuesday's first witness, geologist Philemon Ebiesuwa, took part in the drafting of both letters, though he was not at the offshore platform. Under cross-examination, he said the signers, who included plaintiff Larry Bowoto, were only trying to get the company to negotiate and were not threatening violence.

"We were just yearning for dialogue," Ebiesuwa said. "We never thought of holding people hostage."

The lawyers also gave conflicting accounts of the confrontation.

Stormer said the protesters were planning to leave on the fourth morning after hearing that a representative on shore had negotiated an agreement with Chevron. Without warning, the plaintiffs' lawyer said, military forces arrived early the next morning on helicopters leased from Chevron and started shooting even before they landed, "first tear gas, then bullets."

Two villagers were killed immediately, Stormer said. He said Bowoto, lead plaintiff in the case, ran toward the soldiers with his hands raised, crying, "Don't shoot," and was shot several times. Others were beaten and then held prisoner under brutal conditions for several weeks, he said.

Mittelstaedt said Chevron tried to negotiate with the villagers, who repeatedly promised to leave if certain demands were met and then reneged. After they started demanding ransom, he said, a Chevron Nigeria official - faced with a "ticking time bomb" - called on the Nigerian navy to rescue the hostages.

"The last thing Chevron Nigeria wanted was for anyone to get hurt," Mittelstaedt said.